Siemens SIMATIC ET 200S Operating Instructions Manual page 33

The latch value is preassigned with its RESET state. It is not changed when the SW gate is
opened.
Direct loading of the counter does not cause the indicated stored counter status to be
changed.
If you close the SW gate, counting is only interrupted; this means that when you open the
SW gate again, counting is continued. The digital input DI remains active even when the SW
gate is closed.
Counting is also latched and triggered in isochronous mode with each edge on the digital
input. The counter status that was valid at the time of the last edge before T
the feedback interface.
The Latch Function
Requirement
In order to use this function, the Function DI parameter must be set to "Latch on Positive
Edge".
Description
Figure 2-10
Counter status and latch value are preassigned with their RESET states.
The counting function is started when the SW gate is opened. The 1Count24V begins at the
load value.
The latch value is always the exact counter status at the time of the positive edge on the
digital input DI.
The stored counter status rather than the current counter status is indicated in the feedback
interface. The STS_DI bit indicates the level of the latch signal.
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07
Latch with a Load Value of 0
1Count24V
2.6 Count Modes
is displayed in
i
33